1. Field of the Invention
The present invention relates to a light emitting apparatus which can be used as illumination apparatus, display, light source for backlight of liquid crystal display, etc. and, more particularly, to a light emitting apparatus having high reliability.
2. Description of the Related Art
Some of light sources used for illumination apparatus, backlight of liquid crystal display, etc. employ semiconductor light emitting element. The semiconductor light emitting element consumes less electric power than the conventional light sources, lasts longer and allow it to make the light emitting apparatus smaller, and is therefore preferably used. There is a demand for a light emitting apparatus which emits light with higher output power by using the semiconductor light emitting element.
In a light emitting apparatus of the prior art disclosed in Japanese Unexamined Patent Publication No. 2004-207672, for example, a support member whereon the light emitting element is mounted has wiring conductors that supply electric power to the light emitting element and reflecting walls for reflecting the light emitted by the light emitting element in an emission observing direction. The light emitting element is mounted at the bottom of a recess provided in the support member. The reflecting wall is formed from a laminated metallic member such as tungsten, nickel and silver or the like on the side wall surface of the recess of the support member which is formed mainly from ceramics.
However, with the trend toward higher output power of the light emitting element, the metallic member provided on the support member may experience deterioration including discoloration, due to the light and heat generated by the light emitting element. Silver, in particular, has high reflectivity to the light from the light emitting element and is therefore preferably used in the reflector wall of the support member, but is likely to deteriorate due to the light and heat generated by the light emitting element. As a result, a part of the light generated by the light emitting element is absorbed by the deteriorated silver, thus resulting in decreasing emission output power of the light emitting apparatus.
Also as the light emitting apparatus decreases in thickness, the distance between the side face of the light emitting element mounted on the bottom surface of the recess and the side wall surface of the recess may become smaller. This may cause the metallic member provided on the side wall surface of the recess to be greatly affected by the light emitted by the light emitting element.